Why first ionisation enthalpy of Cr is lower than that of Zn?

Explanation

To understand why the first ionization enthalpy of chromium (Cr) is lower than that of zinc (Zn), we need to analyze their electronic configurations and the stability of the resulting ions after the removal of an electron.

### Step-by-Step Solution:

1. **Identify the Atomic Numbers and Electronic Configurations:**
- Chromium (Cr) has an atomic number of 24. Its electronic configuration is:
\[
\text{Cr: } [\text{Ar}] 3d^5 4s^1
...